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Since ADEOS-2 was launched, JAXA has analyzed on-orbit telemetry routinely in order to verify design and to find any sign of anomaly or degradation. One of the findings is generation power fluctuation of solar array paddle. We have investigated mechanisms of the power fluctuation and reached a scenario, space debris impact on solar cell. The impact might cause short circuit in solar array paddle and drop generation current. To confirm the scenario, we carried out hypervelocity impact tests to the solar array blankets. The investigation and test result are reported in this paper., 資料番号: AA0049206032, レポート番号: JAXA-SP-05-001E

Studies of the flux variability (short- and long-term) of radiation belt particles in the inner magnetosphere are particularly important for improving our understanding of related phenomena and for engineering considerations such as spacecraft anomalies due to space environment effects, including Electro-Static Discharge (ESD) and Single-Event Upset (SEU). Therefore, we must continue radiation measurements and monitoring by satellites. For this purpose, we operated the Technical Data Acquisition Equipment (TEDA) and Space Environment Data Acquisition Equipment (SEDA) on each JAXA application satellite. This paper reviews the current status of radiation measurements using JAXA satellites as well as electrostatic charge potential measured by Potential Monitors (POM) on three satellites (ETS-V for 10 years in GEO orbit, ETS-6 in GTO orbit, and ADEOS in Polar LEO orbit). We assessed the effects of solar activity on the GEO-orbiting Data Relay Test Satellite (DRTS), also known as Kodama in Japanese, which entered the safety mode (slow-spin mode), essentially shutting down all non-critical functions, on 28 Oct. at 1842 (UT). Three-axis attitude control of Kodama was then recovered on 7 November. In this paper, we report what occurred on the satellite and on a high-energy electron enhancement (or Electro Static Discharge (ESD)) alert system using space weather technique. In addition, I will report on the space environment measurement plan and spacecraft charging technology research plan (in-situ measurement including POM on ETS-8 in GEO orbit)., 資料番号: AA0049206003, レポート番号: JAXA-SP-05-001E

資料番号: AA0063347026

資料番号: AA0063347019

This article presents the summary of the tests performed in the frame of an ESA contract EMAGS2. While EMAGS1 concentrated its efforts on basic understanding of Electrostatic Discharge Phenomenon, EMAGS2 mainly consisted in different tests which aimed at: comparing the characteristics of the secondary arcs obtained in an electronic charging environment with those triggered in a plasma environment (inverted voltage gradient conditions in both cases) (tests in plasma gave results representative of those obtained in electron when the energy of the primary discharge was equivalent); assessing the secondary arc triggering sensitivity to materials. Current/voltage thresholds for self-sustained arc have then been determined for different Si and GaAs solar array samples (lower thresholds on GaAs); assessing the influence of the intercells gap width with regard to secondary arcs (higher secondary arc and permanent arc thresholds for large gaps); and determining the effect on solar cells of repetitive primary discharges and non-permanent secondary arcs has been studied (no impact for repetitive primary discharges and secondary arcs with low duration)., 資料番号: AA0049206043, レポート番号: JAXA-SP-05-001E

We present event studies and results of a statistical investigation on charging events seen by the Freja satellite in the auroral zone at 1,500-1,700 km altitude. Charging up to kilovolts is sometimes observed, though lower values are more normal. Comparing to DMSP at 840 km, Freja experiences fewer charging events, but some of them are found in sunlit conditions, which has not been seen on DMSP. No charging event occurred for a density above 2,000 cu cm, though correlation between density and charging otherwise was weak. All charging events show enhanced electron fluxes around or above 10 keV, including enhanced tails up to 100 keV, while electrons around 1 keV instead counteracts charging, as is expected from high secondary yields in this energy range. Simulations using POLAR reproduced moderate charging events, but not the events with kilovolt charging., 資料番号: AA0049206093, レポート番号: JAXA-SP-05-001E

In the space development and utilization, it is very important to understand the interactions between spacecraft/structures and space plasma environment as well as the natural phenomena occurring in space plasma. In order to evaluate the spacecraft-plasma interactions quantitatively to contribute to the progress of space utilization and space technology, we aim to develop a proto model of Geospace Environment Simulator (GES) by making the most use of the conventional full Particle-In-Cell (PIC) plasma simulations. For the development of GES, we have been using the Earth simulator which is one of the fastest supercomputer in the world. GES can be regarded as a numerical chamber in which we can virtually perform space experiments and analyze the temporal and spatial evolution of spacecraft-plasma interactions. GES will be able to provide fundamental data regarding various engineering aspects such as the electrostatic charging and electromagnetic interference of spacecraft immersed in space plasmas, which will be useful and important information in determining designs and detailed specifications of spacecraft and space systems., 資料番号: AA0049206054, レポート番号: JAXA-SP-05-001E

Spacecraft Charging Mitigation is an art form that dates back to the 1960's. The most common practice involves controlling the resistance per unit surface area, and/or the resistance per unit volume of dielectric materials. This is implemented with proper bonding to reference ground to provide a charge bleed-off path. We show how grounding configuration affects the effectiveness of the mitigation method, and we propose a general rule-of-thumb that guarantees optimal results., 資料番号: AA0049206092, レポート番号: JAXA-SP-05-001E

The validation of new solar cell for geostationary satellite application sets the problem of arcing between solar cells triggered by electrostatic discharges (ESD(sup 1)). The main difficulty of a ground test is to properly simulate the transient behavior of one string from the first microsecond of an electrostatic discharge and to take into account all the energy stored on a panel that would be released during hundreds of microseconds. The test set-up to use, with all the physical data we need to take into account, to properly simulate the response of the string to an ESD, is presented in this paper. Since the power losses on the Tempo and Panamsat satellites attributed to electrostatic discharges in 1997 (15 percent of the power in three months), the international scientific community has looked into the problem of sustain arc on solar array. It was therefore necessary to draw up a discharge theory, with a sequencing of events, by taking into account the energy available at the moment of discharge on the satellite presented at the 7th SCTC as on this energy depends the amplitude of the primary discharge, and therefore the associated thermal effect, which totally conditions the arc. On the other hand, manufacturers, now encountering problems of electrostatic nature on satellites (section losses on high voltage solar arrays), present the problem in terms of efficient solutions. Manufacturers and laboratories still test solar array samples with their own assembly configurations which, for a single sample, can either be disastrous or have not the slightest effect. Indeed, depending on whether the energy developed in the primary discharge comes from a capacitor of 100 pF or one of 1 micro-F, the result with regards to the direct effects of the primary discharge and the sustained arc risk will be completely different. To test solar array samples a priori in the confinement of an enclosed vacuum, it is necessary to define a laboratory test set-up, which represents what the solar array comes across in the geostationary orbit. To finalize this test set-up, we had to know the error made when using a 4 cells sample instead of a real large solar array in terms of primary discharge representativity, available energy stored, and electrical response of the simulating circuit. This paper will present electrical circuit needed to be representative of the flight configuration. It will explain how to make your own test set-up depending on the solar cells you want to use. This test set-up take into account the energy stored in the coverglass and the way it has to be released. The solar array test set-up is proposed by CNES in the frame of the ECSS for the European standardization. It does not take in consideration any commercial aspects or feasibility by such-and-such manufacturers. So one could imagine disagreements even oppositions to those propositions whom all are based on pure technical aspects. Although, the draft proposed is based on seven years of experiments, last one of which was shared with Japan to set basis of an universal standardization., 資料番号: AA0049206048, レポート番号: JAXA-SP-05-001E

Due to their dielectric nature and under the effect of the different forms of radiation encountered in space, dielectrics accumulate electrical charges up to the point where electrostatic discharges may occur. To prevent and avoid harmful interference due to discharges, their behavior under irradiation must therefore be investigated in the laboratory before they are used in space applications. A current and widely used practice is to submit the tested materials to the bombardment of monoenergetic electron beams. Such a practice ignores the presence in space of a spectrum of electrons with energies reaching several MeV, and leads solely to surface charging and surface potentials generally higher than those really induced in space. The new approach consists in using in laboratory an electron source as similar as possible to the one existing in orbit. This paper describes the result obtained in the SIRENE facility, which was developed for simulating the spatial geostationary or MEO environment during great geomagnetic activity comparatively with monoenergetic irradiation. The range of available electrons in SIRENE goes from 10 to 400 keV. It points out the effect of the radiated induced conductivity. This paper provides results obtained on classical dielectrics as Teflon, Kapton and Duroid of different thickness under mono and multi-energetic irradiation at ambient temperature and at - 150 C. This paper showed also that even in the case of very low flux of high energy electrons, the surface voltage measured remains deeply affected. Based on those results the usual habit to use monoenergetic irradiation for qualification of space dielectrics should be reconsidered. For example surface voltage obtained of Teflon is lower than the one obtained on Kapton under the same irradiation condition., 資料番号: AA0049206008, レポート番号: JAXA-SP-05-001E

The Special Sensor Ultraviolet Limb Imager (SSULI) was developed by the U.S. Naval Research Laboratory and is deployed on the DMSP F16 polar orbiting spacecraft. The instrument is experiencing a level of noise that is, at times, interfering with its proper operation. The noise is correlated with the spacecraft chassis potential. We computed the potentials about DMSP and the resulting ionospheric currents entering the instrument to determine if the noise could be due to these currents. In order to obtain results of sufficient accuracy, it is necessary to use a reverse trajectory technique that effectively integrates over the thermal distribution of incident ions. The reverse trajectory technique is described in detail. The currents computed using this approach show a strong dependence on the chassis potential that is different from that of the observed noise levels, which suggests that either the noise has another source or other factors reduce the current., 資料番号: AA0049206101, レポート番号: JAXA-SP-05-001E

The ADEOS-2 satellite experienced anomalous operation on October 25, 2003. The power generated on the satellite suddenly decreased from 6 kW to 1 kW. We conducted experiments to investigate this degradation of power for the satellite. The multi-layer insulator film that wraps the power cables was charged by low-energy electrons when the satellite passed though the aurora region around the Earth's pole. ESD tests were carried out for the power cables. Trigger arc discharges occurred between the film and cables with cracks produced by thermal cycles. A secondary arc electric discharge subsequently occurred between the cables themselves. This secondary arc caused a sustained arc after several discharges, which burned out the cables. The heat caused by arc tracking between the hot and return cables made them burn out. This was the mechanism of the operational anomaly on the ADEOS-2 satellite., 資料番号: AA0049206096, レポート番号: JAXA-SP-05-001E

The characterization of the electromagnetic interaction for a solar sail in the solar wind environment and identification of viable charging mitigation strategies are critical solar sail mission design tasks. Spacecraft charging has important implications both for science applications and for lifetime and reliability issues of sail propulsion systems. To that end, surface charging calculations of a candidate 150-meter-class solar sail spacecraft for the 0.5 AU solar polar and 1.0 AU L1 solar wind environments are performed. A model of the spacecraft with candidate materials having appropriate electrical properties is constructed using Object Toolkit. The spacecraft charging analysis is performed using Nascap-2k, the NASA/AFRL sponsored spacecraft charging analysis tool. Nominal and atypical solar wind environments appropriate for the 0.5 AU and 1.0 AU missions are used to establish current collection of solar wind ions and electrons. Finally, a geostationary orbit environment case is included to demonstrate a bounding example of extreme (negative) charging of a solar sail spacecraft. Results from the charging analyses demonstrate that minimal differential potentials (and resulting threat of electrostatic discharge) occur when the spacecraft is constructed entirely of conducting materials, as anticipated from standard guidelines for mitigation of spacecraft charging issues. Examples with dielectric materials exposed to the space environment exhibit differential potentials ranging from a few volts to extreme potentials in the kilovolt range., 資料番号: AA0049206065, レポート番号: JAXA-SP-05-001E

Tests of arcing and current collection in simulated space plasma conditions have been performed at the NASA Glenn Research Center (GRC) in Cleveland, Ohio, for over 30 years and at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, for almost as long. During this period, proper test conditions for accurate and meaningful space simulation have been worked out, comparisons with actual space performance in space flight tests and with real operational satellites have been made, and NASA has achieved our own internal standards for test protocols. It is the purpose of this paper to communicate the test conditions, test procedures, and types of analysis used at NASA GRC and MSFC to the space environmental testing community at large, to help with international space-plasma arcing-testing standardization. To be discussed are: 1. Neutral pressures, neutral gases, and vacuum chamber sizes. 2. Electron and ion densities, plasma uniformity, sample sizes, and Debye lengths. 3. Biasing samples versus self-generated voltages. Floating samples versus grounded. 4. Power supplies and current limits. Isolation of samples from power supplies during arcs. 5. Arc circuits. Capacitance during biased arc-threshold tests. Capacitance during sustained arcing and damage tests. Arc detection. Preventing sustained discharges during testing. 6. Real array or structure samples versus idealized samples. 7. Validity of LEO tests for GEO samples. 8. Extracting arc threshold information from arc rate versus voltage tests. 9. Snapover and current collection at positive sample bias. Glows at positive bias. Kapton pyrolysis. 10. Trigger arc thresholds. Sustained arc thresholds. Paschen discharge during sustained arcing. 11. Testing for Paschen discharge thresholds. Testing for dielectric breakdown thresholds. Testing for tether arcing. 12. Testing in very dense plasmas (i.e., thruster plumes). 13. Arc mitigation strategies. Charging mitigation strategies. Models 14. Analysis of test results. Finally, the necessity of testing will be emphasized, not to the exclusion of modeling, but as part of a complete strategy for determining when and if arcs will occur, and preventing them from occurring in space., 資料番号: AA0049206044, レポート番号: JAXA-SP-05-001E

Arcing on satellite solar array due to interaction with space plasma may cause permanent loss of satellite power, once the arc becomes permanent sustained arc. An arc on solar array becomes a secondary arc when solar array circuit is short-circuited and provides energy to the arc plasma. The permanent sustained arc, the final stage of the secondary arc, destroys a solar array string or the complete power circuits at the worst case. To investigate the threshold conditions for the secondary arc formation, laboratory tests are carried out in a xenon plasma chamber simulating LEO plasma environment with an external circuit simulating a spacecraft power system. Solar array coupon panels simulating the hot and return ends of a string circuit are tested for various combinations of string voltage and string current. Experimental results show that formation of secondary arc strongly depends on the string voltage and duration of secondary arc depends on the string current., 資料番号: AA0049206024, レポート番号: JAXA-SP-05-001E

Neutralization of ion beams in electric propulsion applications is a well-known phenomenon. The physics behind the robust matching of ion and electron currents and densities, are not. As electric propulsion devices move into micro and macro regimes with colloids, FEEPs, and thruster arrays, thruster-neutralizer interactions are under increasing scrutiny. A series of 2D simulations using PIC codes are presented, detailing starting and steady state interactions. It is shown that the expectations of full current coupling of electrons to the beam is not seen, but there is similar coupling behavior exhibited. Numerical mechanisms for coupling the current to the beam are examined for effect on coupling behavior., 資料番号: AA0049206062, レポート番号: JAXA-SP-05-001E

Since the failure of ADEOS-2, charging of satellites in polar orbit has become a serious issue. The Japan Aerospace Exploration Agency has decided to develop a computational tool that can calculate charging status of a polar orbiting satellite jointly with Kyushu Institute of Technology. The simulation code is a combination of a particle-in-cell method and a particle tracking method and can be used not only for a polar satellite but also for a GEO satellite or a low inclination LEO satellite. The aim of the simulation code is to give satellite designers chances to identify the charging hazard in the satellite design phase with user-friendly interface. The development of software, named Multi-utility Spacecraft Charging Analysis Tool (MUSCAT), started in December, 2004. Overview of development plan and current status of the simulation code will be presented., 資料番号: AA0049206055, レポート番号: JAXA-SP-05-001E

As the power level of Geostationary satellites increases, there is more demand of careful ground test on solar array insulation strength. International atmosphere surrounding commercial telecommunication satellites calls for common international standard on test conditions. In this paper, we review ESD tests of solar array carried out in recent years at Kyushu Institute of Technology jointly with the Japan Aerospace Exploration Agency. The purpose of this paper is to describe the test conditions with the reasons of selecting those conditions and how we certified the insulation strength of given solar array designs against electrostatic discharges in orbit. The paper is aimed to stimulate discussion among experts on the issue of international standardization of solar array ESD test., 資料番号: AA0049206046, レポート番号: JAXA-SP-05-001E

When solar array is operated at a high voltage, arcs occur on the array surface. Our task is to examine the effects of conductive current generated by arcing on solar array circuit of spacecraft. First, equivalent circuits of small solar array module are modeled. The equivalent circuits are made for various types of solar cells such as silicon, gallium arsenic (hetero-junction), and triple junction cells, etc. The equivalent circuit is composed of current source, diode, resistance, inductance and capacitance. First, we measured the frequency characteristic and I-V characteristic of a given solar array, and modeled the equivalent circuit to have the same characteristics by electronic circuit simulation software (SPICE). Next, an electric equivalent circuit of the arc inception was made, and was compared with the ground test result. We simulated the transient current and surge voltage resulted from the ground test using the equivalent circuit. The circuit is being adjusted to experimental results at present. We plan to add the effect of arc expansion to the circuit., 資料番号: AA0049206068, レポート番号: JAXA-SP-05-001E

The classical estimations give the maximum potential of spherical satellite (spacecraft) during the electron beam injection in the ionosphere that much exceed the value obtained in real rocket experiments even those conducted at night and without artificial neutralization. The possibilities of compensation are considered on the basis of theoretical models taking into account the collective beam-plasma interactions. The examples of numerical modeling of the charge-discharge dynamics are provided for the APEX spacecraft conditions. It is shown that changing the pulse form and rise rate (dI/dt) can change the structure of space charge zone i.e. try to create the strong disturbance or resonance conditions in the time interval of (pi/omega(sub p)) less than or equal to t less than or equal to t(sub ion). From these positions we consider the APEX facilities used to control the inflow current, the spectrum of energetic particles, the high-frequency oscillations and the spatial distribution of optical emissions in the injector vicinity with high time resolution., 資料番号: AA0049206029, レポート番号: JAXA-SP-05-001E

A magnetic sail is a unique propulsion system, which travels interplanetary space by capturing the energy of the solar wind. In order to simulate the interaction between the artificial magnetic field produced around a spacecraft and the solar wind, scaled-down laboratory experiment was conducted in a space chamber. Preliminary results showed some strong interactions between the high-density and high-velocity plasma flow and an artificial magnetic field, hence the possibility of the magnetic sail simulator is provided; however, further improvement is required to realize a collision-less solar wind plasma flow in the laboratory., 資料番号: AA0049120020

Multijunction (MJ) solar cells have received extensive attention for use in space satellites because of their high efficiency. The radiation tolerance of the cells is important for space applications. Understanding the degradation mechanisms is essential to develop high quality MJ cells, although investigation of the radiation effects in these cells is very difficult because of their complex structure. The purposes of this study were to develop useful methods with which to evaluate radiation effects in the respective sub cells of the MJ cell, and to investigate their degradation mechanisms. We successfully applied selective excitation photoluminescence (PL) and electroluminescence (EL) spectroscopy to analysis of the 1 MeV electron irradiation effects in the MJ cells. The PL peak intensity of band-edge emission from the InGaP2 cell scarcely degraded after irradiation, while that of the GaAs cell decreased considerably. The degradation rate of PL intensity of the Ge cell was less than that of the GaAs cell. The degradation tendencies of EL from the respective sub cells were similar to those of PL measurement. The result of EL spectroscopy paralleled the change in conversion efficiencies of the MJ cells. Shape of the PL spectrum from the GaAs cell changed dramatically except for the emission peak above the band-gap which hardly degraded after the electron irradiation. From these findings, we concluded that the radiation tolerance becomes higher in the order of GaAs, Ge and InGaP2 cells. In addition, we were able to analyze the formation of natural superlattice in the InGP2 cell and determine the doping amount of In in the GaAs cell. We were also able to perform macroscopic and microscopic mappings of PL and EL intensities on the respective sub cells, which were useful for evaluation of the performance uniformity. The characteristic patterns resulting from the dislocations of the cells were observed. We believe that the present study will contribute greatly to the development of highly efficient and highly radiation tolerant MJ cells., 資料番号: AA0049120005

Japan Aerospace Exploration Agency (JAXA) developed piggyback satellite named INDEX. We applied lithium-ion secondary battery based on pouch cells for the satellite. The cell is designed using manganese oxide for the positive electrode and graphite carbon for the negative. The electrolyte for the lithium-ion cell is dissolved by organic solvent. Due to this configuration of the cell, the cell expands under the vacuum conditions. Since the expansion increases the DC impedance of the cell, we observed the degradation of the performance under vacuum conditions. In order to prepare the battery which is tolerant against the vacuum environment, the pouch cells were potted with resin and reinforced by the aluminum housing. More than 3,300 cycles of the charge/discharge performance was confirmed. We also tested the tolerance against the radiation using bare cells, and observed no degradation of capacity. Through these experiments, we confirmed the appropriate performance of the lithium-ion pouch cells for the operations of INDEX., 資料番号: AA0049054023, レポート番号: JAXA-SP-05-008

Li ion cells for space applications possess a high specific energy and a high discharge voltage, and have recently begun to be adopted as space batteries in terms of their lightweight and reliability requirements. A variety of researches have been advanced for various applications. Until now, we have been researching the storage and the management methods of the Li ion cells as the batteries of spacecraft for planetary explorations. Because deterioration of Li ion cells occurs even under their unoperated condition, the research of the storage method is very important for their application to the power supply for the satellites. In general, degradations of charge/discharge characteristics of the Li ion cells are caused when they are stored under open circuit conditions during a long duration. The degradations become severe as their temperature and state of charge (SOC) increase. Then, we investigated charge/discharge characteristics and charge/discharge cycle characteristics of Li ion cells after they had been kept under various temperatures and SOC's for 12 months. As a result, it was confirmed that the deterioration effect of the battery characteristics during the low-temperature storage was extremely small., 資料番号: AA0049120002

第25回宇宙利用シンポジウム(2009年1月14日-15日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan), A space propulsion system and a power generation system using Water-Energy-Cycle of multi-hundred watts are designed and integrated into a standard rack unit compatible to the Space Station "KIBOU". This newly conceptualized system stores hydrogen and oxygen electrolyzed from water by solar cell energy, while in the reverse cycle, these gases are provided into fuel cells to provide electrical power and water. The stored hydrogen and oxygen are also usable for rocket propellants, and furthermore, the water and oxygen are available for the life support system during manned space activities. The stored hydrogen can be also used as reduction of minerals in the lunar base activities in the future. This time, the unit was integrated and dedicated to several ground-based tests with different attitudes against 1 G gravity direction., 形態: カラー図版あり, 資料番号: AA0064297104

Large lithium ion cells in capacity range of 50 to 190 Ah for space applications have been developed and tested. It was evaluated for both calendar life and cycle life characteristics to confirm life performance for satellite applications. From these results, we established a simple formula to calculate cell capacity fade and impedance increase. In addition, we have been conducting various kind of life simulation tests on other cells from different manufacturing lots and confirmed that the cell satisfied general life requirements of these applications. We have verified the model by comparing calculated capacity fade estimates with the simulated life tests. Since our calculated life estimates match the experimental data with a high degree of precision, we feel this demonstrates the validity of our life model., 資料番号: AA0049120003

In the future, LEO spacecraft will be larger and higher powered. Because of the balance of leakage currents through ambient space plasma, their main conductive body will have a higher negative potential without plasma contactor operation. When spacecraft operate with a higher voltage, more intensive arcing is suspected to occur on the surface. In this study ground-based experiment was carried out to understand the arcing phenomenon and to examine influences of ambient space plasma on the arcing process. Simulating plasmas were generated by electron cyclotron resonance discharge. When arcing occurred on negatively-biased anodized aluminum sample (AAS) plates in the plasma environment, the time variations in arc current and bias voltage were measured. Arc spot diameter was also measured. The single arcing characteristics showed that both the peak arc current and the total charge emitted by arcing increased with initial charging voltage and neutral particle number density. The diameter of arc spots increased with initial charging voltage although it was almost constant regardless of neutral particle density. The repetitive arcing characteristics showed that the arc rate gradually increased with arcing number. Lots of overlapping arc spot were observed after 1,000 arcings, and its number increased with arcing number. Accordingly, arc tends to occur at a same location as increasing arcing number. Influences of initial charging energy on arcing characteristics were also examined by widely changing capacitance and initial charging voltage. The arc spot diameter widely increased with initial charging energy, and the fitting line could be evaluated. Unsteady physical processes inside an arc spot, such as ablation and heating of insulator, and plasma generation and acceleration etc., were studied using Computational Fluid Dynamics (CFD). Direct-Simulation-Monte-Carlo Particle-In-Cell (DSMC-PIC) plasma simulation was also carried out to examine influences of ambient space plasma on plasma expansion processes outside the arc spot. The calculated arc current increased with time; had a peak and then decreased. Inside the arc spot, the calculated plasma resistance rapidly decreased with time; was kept low level and jumped just before extinguishment of arc. As a result, the plasma resistance characteristics agreed with the arc current characteristics. The calculated ablation rate rapidly increased with time; had a peak and then gradually decreased, although the calculated arc spot diameter gradually increased with time. Furthermore, the calculated arc spot diameter gradually increased with initial stored energy, although it was smaller than experimental ones. Both the neutral particle number density and the electron number density were the highest near arc initiation and decreased with time. Both the number densities were relatively high inside the arc spot compared with those outside it. The temperature of insulator surface in contact with plasma rapidly increased up to 5,000 K near arc initiation and gradually decreased to 4,000 K. Outside the arc spot, neutral particles in addition to charged particles around spacecraft played an important role in expansion of arc plasma by intensive ionization near the arc spot. Accordingly, high voltage operation of LEO spacecraft might bring drastic degradation of insulator surface by arcing, depending on spacecraft capacitance, insulator material properties and ambient plasma conditions., 資料番号: AA0049120019

Cu(In,Ga)Se2 (CIGS) solar cells have the advantages of low weight and high radiation receptivity, which are quite attractive for the space application. The high radiation tolerance has been explained by the recovery effect during low-temperature annealing. However, the process of the radiation degradation and the annealing effect has not yet been clarified. We investigated the radiation-induced defects in poly-crystalline CIGS by photoluminescence (PL) spectroscopy. The proton irradiation degraded the near band-edge (1.1 eV) emission and induced the deep-level emission at 0.8 eV. We suggest that the radiation-induced defects are responsible for the deep-level emission. The heat treatment at 120 C restored the 1.1 eV emission and reduced the 0.8 eV band. After annealing, the intensity of the 1.1 eV emission from CIGS solar cells became higher than that from CIGS thin films. We suggest that this phenomenon is caused by the difference in the surface/interface conditions of the CIGS layers., 資料番号: AA0049120006

JAXA/ISTAで開発している放射線計測装置の開発経緯と現在開発している軽粒子観測装置のうち低エネルギー電子観測装置の成果について述べる。, 資料番号: AA0048468002, レポート番号: JAXA-SP-04-010

資料番号: AA0048468014, レポート番号: JAXA-SP-04-010

大気光波状構造の生成過程解明を目的とし、2004年1月に行われたロケット・地上観測キャンペーンWAVE2004において、S-310-33号機によって得られた酸素原子密度・大気光放射率高度分布および姿勢の解析結果を述べる。前回のキャンペーンWAVE2000では、酸素原子密度高度分布が鉛直波長10kmの大気波動によって著しく変調されていたため、通常とは異なる状況下で実験が行われたが、今回得られた酸素原子密度高度分布は高度97km付近に単独ピークを示し、各大気光放射率高度分布も典型に近かった。地上観測および前回の情報との比較により、波状構造生成過程の本質に迫ることができると期待される。, A coordinated rocket and ground-based measurement campaign WAVE2004 was carried out in January 2004 to investigate the formation process of the waves in airglow structures. Atomic oxygen density and airglow emission rate distributions obtained on board the sounding rocket S-310-33 and the analysis of rocket attitude are presented., 資料番号: AA0048467001, レポート番号: JAXA-SP-04-007

資料番号: AA0048468011, レポート番号: JAXA-SP-04-010

資料番号: AA0048468003, レポート番号: JAXA-SP-04-010

At the laboratory, the space environment proof test to evaluate the performance of the solar array against arcing is being performed. Since most test facilities are not large enough to accommodate a full solar panel, laboratories usually use coupons. Usually, the capacitance of coverglass is simulated by connecting a capacitor in the external circuit. But, there are big differences among research organizations about how much capacitance is appropriate. The international standard about the ground test conditions does not exist. The purpose of this research is to investigate the influence of coverglass on arcing phenomena on GEO satellite solar array. The experiment is performed by using a large solar array coupon (400 x 400 mm). The coupon has 50 Si cells. Extent of neutralization differs for each arc. Less charge is neutralized as the distance from arc spot increases. At the worst case, 53 percent charge was neutralized at 325 mm. Plasma propagation velocity is of the order of 10(exp 4) m/s but differ widely for each arc., 資料番号: AA0048468010, レポート番号: JAXA-SP-04-010

2003年10月25日(JST)に、環境観測技術試験衛星みどり2(ADEOS-2)の太陽電池パドル発生電力が6kWから1kWに低下する事象が発生し、衛星全損に至る不具合となった。原因調査の結果、電力ハーネスに巻かれたMLIが、オーロラ帯域通過時に帯電し、MLIと電力ハーネスとの間で単発的な放電が繰返され、ついにはパドル電力ハーネス間での持続放電(アークトラッキング)が発生したことにより、電力ハーネスの損傷およびパドル発生電力の低下に至ったことが明らかとなった。, 資料番号: AA0048468017, レポート番号: JAXA-SP-04-010

資料番号: AA0048709001, レポート番号: JAXA-RR-04-044E

JAXAの環境計測技術グループで現在研究開発中の宇宙環境計測技術の研究目的と成果、研究ロードマップおよび各個別開発テーマの概要を報告する。, 資料番号: AA0048468001, レポート番号: JAXA-SP-04-010

資料番号: AA0047900006